U.S. patent application number 10/607366 was filed with the patent office on 2004-05-27 for method and apparatus for improving mitral valve function.
Invention is credited to Cohn, William E., Liddicoat, John R., Streeter, Richard B., Woolfson, Steven B..
Application Number | 20040102839 10/607366 |
Document ID | / |
Family ID | 30003211 |
Filed Date | 2004-05-27 |
United States Patent
Application |
20040102839 |
Kind Code |
A1 |
Cohn, William E. ; et
al. |
May 27, 2004 |
Method and apparatus for improving mitral valve function
Abstract
A method and apparatus for reducing mitral regurgitation. The
apparatus is inserted into the coronary sinus of a patient in the
vicinity of the posterior leaflet of the mitral valve, the
apparatus being configured to straighten the natural curvature of
at least a portion of the coronary sinus in the vicinity of the
posterior leaflet of the mitral valve, whereby to move the
posterior annulus anteriorly and thereby improve leaflet coaptation
and reduce mitral regurgitation.
Inventors: |
Cohn, William E.; (Chestnut
Hill, MA) ; Liddicoat, John R.; (Boston, MA) ;
Woolfson, Steven B.; (Boston, MA) ; Streeter, Richard
B.; (Winchester, MA) |
Correspondence
Address: |
Mark J. Pandiscio
Pandiscio & Pandiscio, P.C.
470 Totten Pond Road
Waltham
MA
02451-1914
US
|
Family ID: |
30003211 |
Appl. No.: |
10/607366 |
Filed: |
June 26, 2003 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10607366 |
Jun 26, 2003 |
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10446470 |
May 27, 2003 |
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60391790 |
Jun 26, 2002 |
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Current U.S.
Class: |
623/2.11 ;
623/2.36 |
Current CPC
Class: |
A61F 2/2451 20130101;
Y10S 623/904 20130101 |
Class at
Publication: |
623/002.11 ;
623/002.36 |
International
Class: |
A61F 002/24 |
Claims
What is claimed is:
1. A method for reducing mitral regurgitation comprising: inserting
apparatus into the coronary sinus of a patient in the vicinity of
the posterior leaflet of the mitral valve, the apparatus being
configured to straighten the natural curvature of at least a
portion of the coronary sinus in the vicinity of the posterior
leaflet of the mitral valve, whereby to move the posterior annulus
anteriorly and thereby improve leaflet coaptation.
2. A method for reducing mitral regurgitation comprising: inserting
apparatus into the coronary sinus of a patient in the vicinity of
the posterior leaflet of the mitral valve, the apparatus being
configured to move at least a portion of the coronary sinus in the
vicinity of the posterior leaflet of the mitral valve anteriorly,
whereby to move the posterior annulus anteriorly and thereby
improve leaflet coaptation.
3. A method for reducing mitral regurgitation comprising: inserting
apparatus into the coronary sinus of a patient in the vicinity of
the posterior leaflet of the mitral valve, the apparatus being
configured to reduce the degree of natural curvature of at least a
portion of the coronary sinus in the vicinity of the posterior
leaflet of the mitral valve, whereby to move the posterior annulus
anteriorly and thereby improve leaflet coaptation.
4. A method for reducing mitral regurgitation comprising: inserting
apparatus into the coronary sinus of a patient in the vicinity of
the posterior leaflet of the mitral valve, the apparatus being
configured to increase the natural radius of curvature of at least
a portion of the coronary sinus in the vicinity of the posterior
leaflet of the mitral valve, whereby to move the posterior annulus
anteriorly and thereby improve leaflet coaptation.
5. A method for reducing mitral regurgitation comprising: inserting
apparatus into the coronary sinus of a patient in the vicinity of
the posterior leaflet of the mitral valve, the apparatus having a
distal end, a proximal end and an intermediate portion, the
apparatus being configured so that when the apparatus is positioned
in the coronary sinus in the vicinity of the posterior leaflet of
the mitral valve, the distal and proximal ends apply a
posteriorly-directed force to the wall of the coronary sinus and
the intermediate portion applies an anteriorly-directed force to
the wall of the coronary sinus, whereby to move the posterior
annulus anteriorly and thereby improve leaflet coaptation.
6. A method for reducing mitral regurgitation comprising: inserting
a substantially straight elongated body into the coronary sinus of
a patient in the vicinity of the posterior leaflet of the mitral
valve, the length of the substantially straight elongated body
being sized relative to the natural curvature of the coronary sinus
in the vicinity of the posterior leaflet of the mitral valve so
that when the substantially straight elongated body is positioned
in the coronary sinus, it causes at least a portion of the coronary
sinus to assume a substantially straight configuration adjacent to
the posterior leaflet of the mitral valve, whereby to increase the
radius of curvature of the mitral annulus and thereby improve
leaflet coaptation.
7. A method for reducing mitral regurgitation comprising: inserting
a substantially rigid elongated body into the coronary sinus of a
patient in the vicinity of the posterior leaflet of the mitral
valve, the substantially rigid elongated body being configured
relative to the natural curvature of the coronary sinus in the
vicinity of the posterior leaflet of the mitral valve so that when
the substantially rigid elongated body is positioned in the
coronary sinus, it causes at least a portion of the coronary sinus
to assume a different configuration adjacent to the posterior
leaflet of the mitral valve, whereby to move the posterior annulus
anteriorly and thereby improve leaflet coaptation.
8. A method for reducing mitral regurgitation comprising: inserting
a substantially straight, substantially rigid elongated body into
the coronary sinus of a patient in the vicinity of the posterior
leaflet of the mitral valve, the length of the substantially
straight, substantially rigid elongated body being sized relative
to the natural curvature of the coronary sinus in the vicinity of
the posterior leaflet of the mitral valve so that when the
substantially straight, substantially rigid elongated body is
positioned in the coronary sinus, it causes at least a portion of
the coronary sinus to assume a substantially straight configuration
adjacent to the posterior leaflet of the mitral valve, whereby to
increase the radius of curvature of the mitral annulus and thereby
improve leaflet coaptation.
9. An apparatus for reducing mitral regurgitation comprising: a
body having a distal end, a proximal end and an intermediate
portion, the body being configured so that when the body is
positioned in the coronary sinus in the vicinity of the posterior
leaflet of the mitral valve, the distal and proximal ends apply a
posteriorly-directed force to the wall of the coronary sinus, and
the intermediate portion applies an anteriorly-directed force to
the wall of the coronary sinus, whereby to move the posterior
annulus of the mitral valve anteriorly and thereby improve leaflet
coaptation.
10. An apparatus for reducing mitral regurgitation comprising: a
substantially straight elongated body adapted to be inserted into
the coronary sinus of a patient in the vicinity of the posterior
leaflet of the mitral valve, the length of the substantially
straight elongated body being sized relative to the natural
curvature of the coronary sinus in the vicinity of the posterior
leaflet of the mitral valve so that when the substantially straight
elongated body is positioned in the coronary sinus, it causes at
least a portion of the coronary sinus to assume a substantially
straight configuration adjacent to the posterior leaflet of the
mitral valve, whereby to increase the radius of curvature of the
mitral annulus, moving the posterior annulus anteriorly, and
thereby improve leaflet coaptation.
11. An apparatus for reducing mitral regurgitation comprising: a
substantially rigid elongated body adapted to be inserted into the
coronary sinus of a patient in the vicinity of the posterior
leaflet of the mitral valve, the length of the straight,
substantially rigid elongated body being sized relative to the
natural curvature of the coronary sinus in the vicinity of the
posterior leaflet of the mitral valve so that when the
substantially rigid elongated body is positioned in the coronary
sinus, it causes at least a portion of the coronary sinus to assume
a different configuration adjacent to the posterior leaflet of the
mitral valve, whereby to move the posterior annulus anteriorly and
thereby improve leaflet coaptation.
12. An apparatus for reducing mitral regurgitation comprising: a
substantially straight, substantially rigid elongated body adapted
to be inserted into the coronary sinus of a patient in the vicinity
of the posterior leaflet of the mitral valve, the length of the
straight, substantially rigid elongated body being sized relative
to the natural curvature of the coronary sinus in the vicinity of
the posterior leaflet of the mitral valve so that when the
substantially straight, substantially rigid elongated body is
positioned in the coronary sinus, it causes at least a portion of
the coronary sinus to assume a substantially straight configuration
adjacent to the posterior leaflet of the mitral valve, whereby to
increase the radius of curvature of the mitral annulus, moving the
mitral annulus anteriorly, and thereby improve leaflet
coaptation.
13. A catheter comprising: a flexible elongated delivery tube
having a central lumen extending from a distal end of said tube to
a proximal end of said tube, the flexibility of said tube being
such as to permit closure of the distal end of said tube upon
encounter with an impinging body structure, whereby to inhibit flow
of fluid out the distal end of said tube; and orifice means defined
by said tube in a side wall thereof, said orifice means being
disposed proximate but spaced from the distal end of said tube, and
configured to permit egress of fluid from said tube.
14. The catheter in accordance with claim 13 wherein said orifice
means comprises at least a selected one of holes,
longitudinally-extending slits, longitudinally-extending slots,
circumferentially-extending slits, circumferentially-extending
slots, gills, and apertures of selected configurations.
15. The catheter in accordance with claim 14 and further
comprising: an outer flexible elongated tube disposed around said
delivery tube and spaced therefrom to define a passageway between
an outer wall of said delivery tube and an inner wall of said outer
tube; wherein the passageway is in communication with said orifice
means.
16. The catheter in accordance with claim 15 wherein the passageway
extends to a proximal end of said outer tube.
17. The catheter in accordance with claim 15 wherein the passageway
is annular in widthwise configuration.
18. A catheter comprising: a flexible elongated delivery tube
having a central lumen extending from a distal end of said tube to
a proximal end of said tube; and longitudinally extending surface
grooves disposed in an outer surface of said tube to permit flow of
fluid longitudinally of said tube.
19. The catheter in accordance with claim 18 wherein said tube is
provided with a second lumen extending alongside the central
lumen.
20. An apparatus for reducing mitral regurgitation, the apparatus
comprising: a body having a distal end, a proximal end, and an
intermediate portion, the body being configured such that when the
body is positioned in the coronary sinus in the vicinity of the
posterior leaflet of the mitral valve, the distal and proximal ends
apply a posteriorly-directed force to the wall of the coronary
sinus, and the intermediate portion applies an anteriorly-directed
force to the wall of the coronary sinus, whereby to move the
posterior annulus of the mitral valve anteriorly and thereby
improve leaflet coaption; and longitudinally extending grooves
disposed in an outer surface of said body to permit flow of fluid
longitudinally of said body.
21. The apparatus in accordance with claim 20 wherein said body is
provided with a central lumen extending from the distal end of said
body to the proximal end of said body.
Description
CROSS-REFERENCE TO RELATED APPLICATION
[0001] This patent application:
[0002] (1) claims benefit of pending prior U.S. Patent Application
Serial No. 60/391,790, filed Jun. 26, 2002, by William E. Cohn et
al. for METHOD AND APPARATUS FOR IMPROVING MITRAL VALVE FUNCTION
(Attorney's Docket No. VIA-34 PROV); and
[0003] (2) is a continuation-in-part of pending prior U.S. patent
application Ser. No. 10/446,470, filed May 27, 2003, by Jonathan M.
Rourke et al. for METHOD AND APPARATUS FOR IMPROVING MITRAL VALVE
FUNCTION (Attorney's Docket No. VIA 43);
[0004] which are incorporated herein by reference.
FIELD OF THE INVENTION
[0005] This invention relates to surgical methods and apparatus in
general, and more particularly to surgical methods and apparatus
for improving mitral valve function.
BACKGROUND OF THE INVENTION
[0006] Mitral valve repair is the procedure of choice to correct
mitral regurgitation of all etiologies. With the use of current
surgical techniques, between 70% and 95% of regurgitant mitral
valves can be repaired. The advantages of mitral valve repair over
mitral valve replacement are well documented. These include better
preservation of cardiac function and reduced risk of
anticoagulant-related hemorrhage, thromboembolism and
endocarditis.
[0007] In current practice, mitral valve surgery requires an
extremely invasive approach that includes a chest wall incision,
cardiopulmonary bypass, cardiac and pulmonary arrest, and an
incision on the heart itself to gain access to the mitral valve.
Such a procedure is associated with high morbidity and mortality.
Due to the risks associated with this procedure, many of the
sickest patients are denied the potential benefits of surgical
correction of mitral regurgitation. In addition, patients with
moderate, symptomatic mitral regurgitation are denied early
intervention and undergo surgical correction only after the
development of cardiac dysfunction.
[0008] Mitral regurgitation is a common occurrence in patients with
heart failure and a source of important morbidity and mortality in
these patients. Mitral regurgitation in patients with heart failure
is caused by changes in the geometric configurations of the left
ventricle, papillary muscles and mitral annulus. These geometric
alterations result in incomplete coaptation of the mitral leaflets
at systole. In this situation, mitral regurgitation is corrected by
plicating the mitral valve annulus, either by sutures alone or by
sutures in combination with a support ring, so as to reduce the
circumference of the distended annulus and restore the original
geometry of the mitral valve annulus.
[0009] More particularly, current surgical practice for mitral
valve repair generally requires that the mitral valve annulus be
reduced in radius by surgically opening the left atrium and then
fixing sutures, or more commonly sutures in combination with a
support ring, to the internal surface of the annulus; this
structure is used to cinch the annulus, in a pursestring-like
fashion, to a smaller radius, thereby reducing mitral regurgitation
by improving leaflet coaptation.
[0010] This method of mitral valve repair, generally termed
"annuloplasty", effectively reduces mitral regurgitation in heart
failure patients. This, in turn, reduces symptoms of heart failure,
improves quality of life and increases longevity. Unfortunately,
however, the invasive nature of mitral valve surgery and the
attendant risks render most heart failure patients poor surgical
candidates. Thus, a less invasive means to increase leaflet
coaptation and thereby reduce mitral regurgitation in heart failure
patients would make this therapy available to a much greater
percentage of patients.
[0011] Mitral regurgitation also occurs in approximately 20% of
patients suffering acute myocardial infarction. In addition, mitral
regurgitation is the primary cause of cardiogenic shock in
approximately 10% of patients who develop severe hemodynamic
instability in the setting of acute myocardial infarction. Patients
with mitral regurgitation and cardiogenic shock have about a 50%
hospital mortality. Elimination of mitral regurgitation in these
patients would be of significant benefit. Unfortunately, however,
patients with acute mitral regurgitation complicating acute
myocardial infarction are particularly high-risk surgical
candidates, and are therefore not good candidates for a traditional
annuloplasty procedure. Thus, a minimally invasive means to effect
a temporary reduction or elimination of mitral regurgitation in
these critically ill patients would afford them the time to recover
from the myocardial infarction or other acute life-threatening
events and make them better candidates for medical, interventional
or surgical therapy.
SUMMARY OF THE INVENTION
[0012] As a result, one object of the present invention is to
provide an improved method and apparatus for reducing mitral
regurgitation.
[0013] Another object of the present invention is to provide a
method and apparatus for reducing mitral regurgitation which is
minimally invasive.
[0014] Another object of the present invention is to provide a
method and apparatus for reducing mitral regurgitation which can be
deployed either permanently (e.g., for patients suffering from
heart failure) or temporarily (e.g., for patients suffering from
mitral regurgitation with acute myocardial infarction).
[0015] These and other objects are addressed by the present
invention, which comprises an improved method and apparatus for
reducing mitral regurgitation.
[0016] In one form of the invention, there is provided a method for
reducing mitral regurgitation comprising:
[0017] inserting apparatus into the coronary sinus of a patient in
the vicinity of the posterior leaflet of the mitral valve, the
apparatus being adapted to straighten the natural curvature of at
least a portion of the coronary sinus in the vicinity of the
posterior leaflet of the mitral valve, whereby to move the
posterior annulus anteriorly and thereby improve leaflet
coaptation.
[0018] In another form of the invention, there is provided a method
for reducing mitral regurgitation comprising:
[0019] inserting apparatus into the coronary sinus of a patient in
the vicinity of the posterior leaflet of the mitral valve, the
apparatus being adapted to move at least a portion of the coronary
sinus in the vicinity of the posterior leaflet of the mitral valve
anteriorly, whereby to move the posterior annulus anteriorly and
thereby improve leaflet coaptation.
[0020] In another form of the invention, there is provided a method
for reducing mitral regurgitation comprising:
[0021] inserting apparatus into the coronary sinus of a patient in
the vicinity of the posterior leaflet of the mitral valve, the
apparatus being adapted to reduce the degree of natural curvature
of at least a portion of the coronary sinus in the vicinity of the
posterior leaflet of the mitral valve, whereby to move the
posterior annulus anteriorly and thereby improve leaflet
coaptation.
[0022] In another form of the invention, there is provided a method
for reducing mitral regurgitation comprising:
[0023] inserting apparatus into the coronary sinus of a patient in
the vicinity of the posterior leaflet of the mitral valve, the
apparatus being adapted to increase the natural radius of curvature
of at least a portion of the coronary sinus in the vicinity of the
posterior leaflet of the mitral valve, whereby to move the
posterior annulus anteriorly and thereby improve leaflet
coaptation.
[0024] In another form of the invention, there is provided a method
for reducing mitral regurgitation comprising:
[0025] inserting apparatus into the coronary sinus of a patient in
the vicinity of the posterior leaflet of the mitral valve, the
apparatus having a distal end, a proximal end and an intermediate
portion, the apparatus being configured so that when the apparatus
is positioned in the coronary sinus in the vicinity of the
posterior leaflet of the mitral valve, the distal and proximal ends
apply a posteriorly-directed force to the wall of the coronary
sinus and the intermediate portion applies an anteriorly-directed
force to the wall of the coronary sinus, whereby to move the
posterior annulus anteriorly and thereby improve leaflet
coaptation.
[0026] In another form of the invention, there is provided a method
for reducing mitral regurgitation comprising:
[0027] inserting a substantially straight elongated body into the
coronary sinus of a patient in the vicinity of the posterior
leaflet of the mitral valve, the length of the substantially
straight elongated body being sized relative to the natural
curvature of the coronary sinus in the vicinity of the posterior
leaflet of the mitral valve so that when the substantially straight
elongated body is positioned in the coronary sinus, it will cause
at least a portion of the coronary sinus to assume a substantially
straight configuration adjacent to the posterior leaflet of the
mitral valve, whereby to increase the radius of curvature of the
mitral annulus and thereby improve leaflet coaptation.
[0028] In another form of the invention, there is provided a method
for reducing mitral regurgitation comprising:
[0029] inserting a substantially rigid elongated body into the
coronary sinus of a patient in the vicinity of the posterior
leaflet of the mitral valve, the substantially rigid elongated body
being configured relative to the natural curvature of the coronary
sinus in the vicinity of the posterior leaflet of the mitral valve
so that when the substantially rigid elongated body is positioned
in the coronary sinus, it causes at least a portion of the coronary
sinus to assume a different configuration adjacent to the posterior
leaflet of the mitral valve, whereby to move the posterior annulus
anteriorly and thereby improve leaflet coaptation.
[0030] In another form of the invention, there is provided a method
for reducing mitral regurgitation comprising:
[0031] inserting a straight, substantially rigid elongated body
into the coronary sinus of a patient in the vicinity of the
posterior leaflet of the mitral valve, the length of the straight,
substantially rigid elongated body being sized relative to the
natural curvature of the coronary sinus in the vicinity of the
posterior leaflet of the mitral valve so that when the straight,
substantially rigid elongated body is positioned in the coronary
sinus, it will cause at least a portion of the coronary sinus to
assume a substantially straight configuration adjacent to the
posterior leaflet of the mitral valve, whereby to increase the
radius of curvature of the mitral annulus and thereby improve
leaflet coaptation.
[0032] In another form of the invention, there is provided an
apparatus for reducing mitral regurgitation comprising:
[0033] a body having a distal end, a proximal end and an
intermediate portion, the body being configured so that when the
body is positioned in the coronary sinus in the vicinity of the
posterior leaflet of the mitral valve, the distal and proximal ends
apply a posteriorly-directed force to the wall of the coronary
sinus, and the intermediate portion applies an anteriorly-directed
force to the wall of the coronary sinus, whereby to move the
posterior annulus of the mitral valve anteriorly and thereby
improve leaflet coaptation.
[0034] In another form of the invention, there is provided an
apparatus for reducing mitral regurgitation comprising:
[0035] a substantially straight elongated body adapted to be
inserted into the coronary sinus of a patient in the vicinity of
the posterior leaflet of the mitral valve, the length of the
substantially straight elongated body being sized relative to the
natural curvature of the coronary sinus in the vicinity of the
posterior leaflet of the mitral valve so that when the
substantially straight elongated body is positioned in the coronary
sinus, it causes at least a portion of the coronary sinus to assume
a substantially straight configuration adjacent to the posterior
leaflet of the mitral valve, whereby to increase the radius of
curvature of the mitral annulus, moving it anteriorly, and thereby
improve leaflet coaptation.
[0036] In another form of the invention, there is provided an
apparatus for reducing mitral regurgitation comprising:
[0037] a substantially rigid elongated body adapted to be inserted
into the coronary sinus of a patient in the vicinity of the
posterior leaflet of the mitral valve, the length of the straight,
substantially rigid elongated body being sized relative to the
natural curvature of the coronary sinus in the vicinity of the
posterior leaflet of the mitral valve so that when the
substantially rigid elongated body is positioned in the coronary
sinus, it causes at least a portion of the coronary sinus to assume
a different configuration adjacent to the posterior leaflet of the
mitral valve, whereby to move the posterior annulus anteriorly and
thereby improve leaflet coaptation.
[0038] In another form of the invention, there is provided an
apparatus for reducing mitral regurgitation comprising:
[0039] a straight, substantially rigid elongated body adapted to be
inserted into the coronary sinus of a patient in the vicinity of
the posterior leaflet of the mitral valve, the length of the
straight, substantially rigid elongated body being sized relative
to the natural curvature of the coronary sinus in the vicinity of
the posterior leaflet of the mitral valve so that when the
straight, substantially rigid elongated body is positioned in the
coronary sinus, it will cause at least a portion of the coronary
sinus to assume a substantially straight configuration adjacent to
the posterior leaflet of the mitral valve, whereby to increase the
radius of curvature of the mitral annulus, moving it anteriorly,
and thereby improve leaflet coaptation.
[0040] In accordance with a further feature of the present
invention, there is provided a catheter comprising a flexible
elongated delivery tube having a central lumen extending from a
distal end of the tube to a proximal end of the tube, the
flexibility of the tube being such as to permit closure of the
distal end of the tube upon encounter with an impinging body
structure, whereby to inhibit flow of fluid out of the distal end
of the tube. Orifice means defined by the tube are disposed in a
side wall thereof, the orifice means being disposed proximate but
spaced from the distal end of the tube and configured to permit
egress of fluid from the tube.
[0041] In accordance with a further feature of the invention, there
is provided a catheter comprising a flexible elongated delivery
tube having a central lumen extending from a distal end of the tube
to a proximal end of the tube, and longitudinally extending surface
grooves disposed in an outer surface of the tube to permit flow of
fluid longitudinally of the tube.
[0042] In accordance with a still further feature of the invention,
there is provided an apparatus for reducing mitral regurgitation.
The apparatus comprises a body having a distal end, a proximal end,
and an intermediate portion, the body being configured such that
when the body is positioned in the coronary sinus in the vicinity
of the posterior leaflet of the mitral valve, the distal and
proximal ends apply a posteriorly-directed force to the wall of the
coronary sinus, and the intermediate portion applies an
anteriorly-directed force to the wall of the coronary sinus,
whereby to move the posterior annulus of the mitral valve
anteriorly and thereby improve leaflet coaptation. Longitudinally
extending surface grooves are disposed in an outer surface of the
body to permit flow of fluid longitudinally of the body.
[0043] Significantly, the present invention may be practiced in a
minimally invasive manner, either permanently or temporarily, so as
to reduce mitral regurgitation.
BRIEF DESCRIPTION OF THE DRAWINGS
[0044] These and other objects and features of the present
invention will be more fully disclosed or rendered obvious by the
following detailed description of the preferred embodiments of the
invention, which is to be considered together with the accompanying
drawings wherein like numbers refer to like parts and further
wherein:
[0045] FIG. 1 is a schematic view of portions of the human vascular
system;
[0046] FIG. 2 is a schematic view of portions of the human
heart;
[0047] FIG. 3 is a schematic view of a preferred system formed in
accordance with the present invention;
[0048] FIGS. 4-7 are a series of views illustrating use of the
system of FIG. 3 to reduce mitral regurgitation;
[0049] FIG. 8 shows an alternative form of delivery catheter;
[0050] FIG. 9 shows an alternative form of flexible push rod;
[0051] FIG. 9A shows another alternative form of the present
invention;
[0052] FIGS. 10 and 11 show alternative constructions for the
straight, substantially rigid elongated body;
[0053] FIG. 12 shows an alternative system formed in accordance
with the present invention;
[0054] FIG. 13 shows use of the system shown in FIG. 12;
[0055] FIG. 14 is a schematic view of a known catheter shown being
used in the introduction of a substantially straight, substantially
rigid elongated body into place to reduce mitral regurgitation, and
encountering a common problem;
[0056] FIG. 15 is a schematic view similar to FIG. 14 but
illustrating an alternative catheter providing a solution to the
aforesaid problem;
[0057] FIG. 16 is an enlarged sectional view of a portion of the
catheter of FIG. 15;
[0058] FIG. 17 is a side elevational view of a further alternative
catheter;
[0059] FIG. 18 is a sectional view taken along line XVIII-XVIII of
FIG. 17;
[0060] FIG. 19 is a side elevational view of a still further
alternative catheter; and
[0061] FIG. 20 is a sectional view taken along line XX-XX of FIG.
19.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0062] The coronary sinus is the largest vein in the human heart.
During a large portion of its course in the atrioventricular
groove, the coronary sinus typically extends adjacent to the left
atrium of the heart for a distance of approximately 5 to 10
centimeters. Significantly, for a portion of its length, e.g.,
typically approximately 7-9 cm, the coronary sinus extends
substantially adjacent to the posterior perimeter of the mitral
annulus. The present invention takes advantage of this fact. More
particularly, by deploying novel apparatus in the coronary sinus,
adjacent to the posterior leaflet of the mitral valve, the natural
curvature of the coronary sinus may be modified in the vicinity of
the posterior leaflet of the mitral valve, whereby to move the
posterior annulus anteriorly so as to improve leaflet coaptation
and, as a result, reduce mitral regurgitation.
[0063] In one preferred embodiment of the invention, the novel
apparatus comprises a straight, substantially rigid elongated body,
the length of the straight, substantially rigid elongated body
being sized so that when the straight, substantially rigid body is
positioned in the coronary sinus in the vicinity of the posterior
leaflet of the mitral valve, the straight, substantially rigid
elongated body will cause at least a portion of the coronary sinus
to assume a substantially straight configuration adjacent to the
posterior leaflet of the mitral valve, whereby to move the
posterior annulus anteriorly and thereby improve leaflet
coaptation.
[0064] And in one preferred embodiment of the invention, access to
the coronary sinus is gained percutaneously, e.g., the straight,
substantially rigid elongated body is introduced into the patient's
vascular system via the jugular vein or via the left subclavian
vein, passed down the superior vena cava, passed through the right
atrium and then passed into the coronary sinus, where it is
deployed. Alternatively, the straight, substantially rigid
elongated body may be introduced into the coronary sinus through a
small incision in the heart, or through some other incision into
the patient's vascular system.
[0065] And in one preferred embodiment of the invention, the
straight, substantially rigid elongated body is guided into
position by (i) passing it through a pre-positioned catheter, or
(ii) passing it over a pre-positioned guidewire, or (iii) passing
it guide-free (e.g., on the end of a steerable delivery tool) to
the surgical site.
[0066] Once deployed, the novel apparatus may be left in position
permanently (e.g., in the case of patients suffering from mitral
regurgitation associated with heart failure) or the novel apparatus
may be left in position only temporarily (e.g., in the case of
patients suffering from mitral regurgitation associated with acute
myocardial infarction).
[0067] Visualization of the procedure may be obtained by
fluoroscopy, echocardiography, intravascular ultrasound,
angioscopy, real-time magnetic resonance imaging, etc. The efficacy
of the procedure may be determined through echocardiography,
although other imaging modalities may also be suitable.
[0068] Looking now at FIG. 1, there are shown aspects of the
cardiovascular system 3 of a patient. More particularly,
cardiovascular system 3 generally comprises the heart 6, the
superior vena cava 9, the right subclavian vein 12, the left
subclavian vein 15, the jugular vein 18, and the inferior vena cava
21. Superior vena cava 9 and inferior vena cava 21 communicate with
the heart's right atrium 24. The coronary ostium 27 leads to
coronary sinus 30. At the far end 31 (FIG. 2) of coronary sinus 30,
the vascular structure turns into the vertically-descending
anterior interventricular vein ("AIV") 32 (see FIG. 1). For
purposes of the present invention, it can generally be convenient
to consider the term "coronary sinus" to mean the vascular
structure extending between coronary ostium 27 and AIV 32.
[0069] As seen in FIG. 2, between coronary ostium 27 and AIV 32,
coronary sinus 30 generally extends substantially adjacent to the
posterior perimeter of the annulus 33 of the mitral valve 36.
Mitral valve 36 comprises a posterior leaflet 39 and an anterior
leaflet 42. In the case of a regurgitant mitral valve, posterior
leaflet 39 and anterior leaflet 42 will generally fail to properly
coapt at systole, thereby leaving an intervening gap 45 which will
permit regurgitation.
[0070] Looking next at FIG. 3, there is shown a system 100 which
comprises one preferred embodiment of the present invention. More
particularly, system 100 generally comprises a guidewire 103, a
delivery catheter 106 and a push rod 109.
[0071] Guidewire 103 comprises a flexible body 112 having a distal
end 115 and a proximal end 118. The distal end 115 of guidewire 103
preferably includes a spring tip 121 for allowing the distal end of
guidewire 106 to atraumatically traverse vascular structures, i.e.,
while the guidewire is being passed through the vascular system of
a patient.
[0072] Delivery catheter 106 comprises a flexible body 124 having a
distal end 127 and a proximal end 130, preferably with an
adjustable valve 133 attached. A central lumen 136 extends from
distal end 127 to proximal end 130. In some circumstances it may be
desirable to provide a securing mechanism for securing the distal
end of the delivery catheter within a vascular structure. By way of
example but not limitation, a balloon 139 may be positioned about
the exterior of flexible body 124, just proximal to distal end 127,
with an inflation lumen 142 extending between balloon 139 and an
inflation fitting 145.
[0073] Push rod 109 comprises a flexible body 148 having a distal
end 151 and a proximal end 154. A straight, substantially rigid
elongated body 157, which may have a variety of different lengths,
is formed on flexible body 148, proximal to distal end 151. A
removable proximal stiffener or handle 160 may be placed between
straight, substantially rigid elongated body 157 and proximal end
154.
[0074] System 100 may be used as follows to reduce mitral
regurgitation.
[0075] First, distal end 115 of guidewire 103 is passed down the
jugular vein 18 (or the left subclavian vein 15) of a patient, down
superior vena cava 9, through right atrium 24 of the heart, and
then into coronary sinus 30. See FIG. 4. It will be appreciated
that as flexible guidewire 103 is passed down coronary sinus 30,
the guidewire will tend to assume the natural curved shape of the
coronary sinus, due to the flexible nature of the guidewire. The
guidewire's atraumatic spring tip 121 will help ensure minimal
damage to vascular structures as guidewire 103 is maneuvered into
position.
[0076] Next, distal end 127 of delivery catheter 106 is placed over
proximal end 118 of guidewire 103 and passed down the guidewire
until the distal end of the delivery catheter is positioned in
coronary sinus 30. See FIG. 5. Again, it will be appreciated that
as the flexible delivery catheter 106 passes down the coronary
sinus, the delivery catheter will tend to assume the natural curved
shape of the coronary sinus, due to the flexible nature of the
delivery catheter.
[0077] Once delivery catheter 106 has been positioned within the
coronary sinus, guidewire 103 is removed. See FIG. 6. Either before
or after guidewire 103 is removed, balloon 139 may be inflated so
as to secure distal end 127 of delivery catheter 106 in position
within coronary sinus 30.
[0078] Next, push rod 109 is passed down the central lumen 136 of
delivery catheter 106. As the push rod's straight, substantially
rigid elongated body 157 is passed down central lumen 136 of
delivery catheter 106, it will force the delivery catheter to
assume a straight configuration at the point where the straight,
substantially rigid elongated body 157 currently resides. As push
rod 109 is pushed down delivery catheter 106, balloon 139 will hold
the distal end of the delivery catheter in position within coronary
sinus 30.
[0079] Push rod 109 is pushed down delivery catheter 106, utilizing
removable proximal stiffener 160 as needed, until the straight,
substantially rigid elongated body 157 is located adjacent to the
posterior annulus of mitral valve 36. See FIG. 7. As this occurs,
the presence of the straight, substantially rigid elongated body
157 in delivery catheter 106 will cause at least a portion of
coronary sinus 30 to assume a substantially straight configuration
at this point, so that the posterior annulus of mitral valve 36 is
forced anteriorly. This will cause the mitral valve's posterior
leaflet 39 to also move anteriorly so as to improve mitral valve
leaflet coaptation and thereby reduce (or completely eliminate)
mitral valve regurgitation. In this respect it should be
appreciated that the posterior annulus may be shifted anteriorly so
as to achieve, or to attempt to achieve to the extent anatomically
possible, leaflet-to-leaflet engagement or leaflet-to-annulus
engagement (e.g., where a leaflet may be tethered due to left
ventricular distortion). Both of these types of engagement, or
targeted engagement, are intended to be encompassed by the terms
"improved leaflet coaptation" and/or "increased leaflet coaptation"
and the like. Using standard visualization means (e.g.
echocardiography or fluoroscopy), the exact position of the
straight, substantially rigid elongated body 157 is adjusted so as
to reduce (or completely eliminate) regurgitation in mitral valve
36.
[0080] In this respect it should be appreciated that the straight,
substantially rigid elongated body 157 is preferably sized to be
somewhat less than the length of the coronary sinus between
coronary ostium 27 and AIV 32. However, in some circumstances it
may be desirable to size the straight, substantially rigid
elongated body 157 so that it will extend out of the coronary sinus
and into the right atrium.
[0081] Furthermore, it should also be appreciated that the system
provides a degree of tactile feedback to the user during
deployment. More particularly, substantial resistance will
typically be encountered as the straight, substantially rigid
elongated body 157 is pushed out of right atrium 24 and into
coronary sinus 30; then resistance will typically drop as body 157
is moved through the coronary sinus; and then resistance will
typically increase significantly again as the distal tip of body
157 comes to the far end 31 of the coronary sinus. Thus, there is a
sort of tactile "sweet spot" when the straight, substantially rigid
elongated body 157 is located in the coronary sinus between
coronary ostium 27 and AIV 32, and this tactile "sweet spot" can be
helpful to the user in positioning the straight, substantially
rigid elongated body 157 in coronary sinus 30.
[0082] At this point the straight, substantially rigid elongated
body 157 is locked in position, e.g., by closing an adjustable
valve 133, and balloon 139 may be deflated.
[0083] System 100 is left in this position until it is no longer
needed. In some cases this may mean that system 100 is left in
position for a period of a few hours, days or weeks; in other cases
system 100 may be substantially permanent. If and when system 100
is to be removed, push rod 109 is removed from delivery catheter
106, and then delivery catheter 106 is removed from the
patient.
[0084] Thus it will be seen that with the present invention, the
straight, substantially rigid elongated body 157 is essentially
force-fit into the normally curved portion of the coronary sinus
adjacent to the mitral valve's posterior leaflet. By properly
sizing the length of the straight, substantially rigid elongated
body 157 relative to the natural curvature of the patient's
anatomy, and by properly positioning the straight, substantially
rigid elongated body 157 in the patient's coronary sinus, the
straight, substantially rigid elongated body will cause at least a
portion of the coronary sinus to assume a substantially straight
configuration adjacent to the posterior leaflet of the mitral
valve. This action will in turn drive the posterior annulus of the
mitral valve anteriorly, so as to improve leaflet coaptation and
thereby reduce mitral regurgitation. Thus, by inserting the
straight, substantially rigid elongated body 157 into the coronary
sinus adjacent to the posterior leaflet of the mitral valve, the
annulus of the mitral valve is effectively manipulated so that it
will assume an increased radius of curvature.
[0085] It has also been found that by inserting the straight,
substantially rigid elongated body into the coronary sinus adjacent
to the posterior leaflet of the mitral valve, the left ventricle
may also be remodeled so as to help alleviate congestive heart
failure.
[0086] It is significant to note that with the present invention,
the distal and proximal ends of straight, substantially rigid
elongated body 157 apply a posteriorly-directed force on the walls
of coronary sinus 30 (e.g., as shown with arrows P in FIG. 7) while
the intermediate portion of straight, substantially rigid elongated
body 157 applies an anteriorly-directed force on the walls of
coronary sinus 30 (e.g., as shown with arrows A in FIG. 7).
[0087] In some cases the proximal end 130 of delivery catheter 106
may be fixed to the patient's outer skin using standard patient
care methods such as adhesive tape, pursestring sutures, skin
staples, etc. In other cases proximal end 130 of delivery catheter
106 may include a sewing cuff whereby the delivery catheter may be
secured to the patient's tissue by suturing. See, for example, FIG.
8, where a sewing cuff 166 is shown attached to the proximal end
130 of delivery catheter 106. If desired, an element 169 may be
provided proximal to adjustable valve 133, whereby flexible push
rod 109 may be made fast to delivery catheter 106. By way of
example, element 169 may comprise a crimpable element to secure
flexible push rod 109 to delivery catheter 106, which is in turn
secured to the patient. If desired, the proximal end of the
assembly may be embedded under the skin of the patient, e.g., in
the case of a permanent implant.
[0088] As noted above, it can be helpful to anchor the distal end
of delivery catheter 106 in position within the coronary sinus
prior to pushing push rod 109 into the delivery catheter. Such an
arrangement will keep the delivery catheter in place as the push
rod makes the turn within the right atrium and enters the coronary
sinus. In the absence of such anchoring, the push rod may drive the
delivery catheter down the inferior vena cava 21. By securing the
distal end of delivery catheter 106 to the walls of coronary sinus
30, the delivery catheter can be stabilized against diversion down
the inferior vena cava 21 when the straight, substantially rigid
elongate body 157 encounters initial resistance to making the turn
into the coronary sinus.
[0089] The balloon 139 is one way of accomplishing such anchoring.
However, it is also possible to utilize other types of securing
mechanisms to anchor the distal end 127 of delivery catheter 106 in
position within coronary sinus 30, e.g., spring clips, ribs,
etc.
[0090] Alternatively, and looking next at FIG. 9, the distal end
151 of push rod 109 may itself be provided with a distal anchor,
e.g., such as the distal anchor 172 shown in FIG. 9.
[0091] It is also possible to prevent diversion of delivery
catheter 106 down inferior vena cava 21 without anchoring the
distal end of delivery catheter 106 or flexible push rod 109 to the
walls of the coronary sinus. More particularly, and looking now at
FIG. 9A, there is shown a support catheter 173 which is formed out
of a more rigid material than delivery catheter 106. Support
catheter 173 is constructed so that its distal end 174 can be
positioned in coronary ostium 27 and then its sidewall 174A can
support delivery catheter 106 adjacent to inferior vena cava 21
when push rod 109 is passed down delivery catheter 106, whereby to
prevent delivery catheter 106 from diverting down inferior vena
cava 106. FIG. 9A also shows an introducer catheter 174B at the
entrance to jugular vein 18.
[0092] As noted above, as push rod 109 is advanced to the region
adjacent to the posterior annulus of the mitral valve, the
straight, substantially rigid elongated body 157 will distort the
natural configuration of the coronary sinus so that it will assume
a substantially straight configuration. While this action induces
the desired valve remodeling, it can also induce a significant
stress on the walls of the coronary sinus, particularly at the
distal and proximal ends of the straight, substantially rigid
elongated body 157, where stress will be concentrated. To this end,
the construction of the straight, substantially rigid elongated
body 157 may be modified somewhat so as to better distribute this
stress. More particularly, and looking next at FIG. 10, the distal
and proximal ends of straight, substantially rigid elongated body
157 may include relatively flexible portions 175 to help better
distribute the stress exerted on the walls of the coronary sinus.
Additionally, and/or alternatively, any taper applied to the distal
and proximal ends of straight, substantially rigid elongated body
157 may be elongated, e.g., such as shown at 178 in FIG. 11, so as
to better distribute the stress imposed on the walls of the
coronary sinus.
[0093] Looking next at FIG. 12, there is shown a system 181 which
comprises another preferred embodiment of the present invention.
More particularly, system 181 generally comprises the guidewire
103, a straight, substantially rigid elongated body 184 and a push
cannula 187.
[0094] Guidewire 103 is as previously described.
[0095] Straight, substantially rigid elongated body 184, which may
have a variety of different lengths, comprises a distal end 188 and
a proximal end 190. A central lumen 193 extends between distal end
188 and proximal end 190. Central lumen 193 accommodates guidewire
103.
[0096] Push cannula 187 comprises a distal end 194 and a proximal
end 196. A central lumen 199 extends between distal end 194 and
proximal end 196. Central lumen 199 accommodates guidewire 103.
[0097] System 181 may be used as follows to reduce mitral
regurgitation.
[0098] First, distal end 115 of guidewire 103 is passed down
jugular vein 18 (or the left subclavian vein 15) of a patient, down
superior vena cava 9, through right atrium 24 of the heart, and
into coronary sinus 30. It will be appreciated that as flexible
guidewire 103 is passed down coronary sinus 30, the guidewire will
tend to assume the natural curved shape of the coronary sinus, due
to the flexible nature of the guidewire. The guidewire's atraumatic
spring tip 121 will help minimize damage to vascular structures as
the guidewire is advanced into position.
[0099] Next, distal end 188 of straight, substantially rigid
elongated body 184 is placed over proximal end 118 of guidewire 103
and passed a short distance down the guidewire. Then the distal end
194 of push cannula 187 is placed over proximal end 118 of
guidewire 103, and then push cannula 187 is advanced down the
guidewire. As push cannula 187 is advanced down the guidewire, its
distal end 194 pushes the straight, substantially rigid elongated
body 184 ahead of it. See FIG. 13.
[0100] As the straight, substantially rigid elongated body 184 is
passed down the coronary sinus, it will force the coronary sinus to
assume a straight configuration at the point where the straight,
substantially rigid elongated body 184 currently resides. Push
cannula 187 is pushed down guidewire as needed, until the straight,
substantially rigid elongated body 184 is located adjacent to the
posterior annulus of the mitral valve. As this occurs, the presence
of the straight, substantially rigid elongated body 184 in the
coronary sinus will cause coronary sinus to assume a substantially
straight configuration at this point, so that the posterior annulus
of the mitral valve is forced anteriorly. This will cause the
posterior mitral valve leaflet to also move anteriorly so as to
improve leaflet coaptation and thereby reduce (or completely
eliminate) mitral valve regurgitation. Using standard visualization
means (e.g. echocardiography or fluoroscopy), the exact position of
the straight, substantially rigid elongated body may be adjusted so
as to reduce (or completely eliminate) regurgitation in the mitral
valve.
[0101] If desired, the push cannula 187 may be provided with a
releasably attachable interface (e.g., a grasper) so that it may
releasably secure the proximal end 190 of the straight,
substantially rigid elongated body 184. Such a feature will permit
the straight, substantially rigid elongated body to be pulled
backward within the coronary sinus, either for positioning or
removal purposes.
[0102] Alternatively, elongated body 184 or 157 may have any of a
variety of non-straight shapes along its length. For example, the
elongated body may be wavy, spiraled, or curved along all or a
portion of its length. By way of example, elongated body 157 and/or
184 may have a curved configuration so as to invert the natural
curvature of the coronary sinus, i.e., so that it is bowed towards
the anterior annulus. Or the elongated body may have a compound
shape along its length, e.g., it may have a sort of "w" shape, with
the center of the "w" being directed towards the anterior annulus.
Any of these or other alternate shapes may effect the anterior
displacement of the posterior annulus that results in reduction of
the mitral valve regurgitation.
[0103] In other alternative embodiments, the elongated body may be
flexible along at least a portion of its length. Regional
flexibility and regional stiffness may allow for straightening of
select locations of the coronary sinus and corresponding locations
of the posterior mitral annulus. This can cause regions of the
mitral annulus to move anteriorly, thus causing regional
improvements in leaflet coaptation. In addition, the elongated body
may be formed by two end segments connected together by a filament:
by anchoring the two end segments relative to the anatomy and
pulling the filament taught, the naturally curved wall of the
coronary sinus can be straightened, whereby to move the posterior
mitral annulus anteriorly and thereby reduce mitral
regurgitation.
[0104] In the preceding discussion, elongated body 157 (or 184) is
generally described as being substantially straight and
substantially rigid, with or without relatively flexible portions
175 (FIG. 10) and/or tapers 178 (FIG. 11). However, it should be
appreciated that the terms "substantially straight", "substantially
rigid", "relatively flexible", and the like, are meant to be
interpreted in the context of the anatomical tissue involved and
should not be interpreted in an absolute sense.
[0105] Fundamentally, elongated body 157 (or 184) is constructed so
that (1) its intermediate portion imparts an anteriorly-directed
force on the walls of the coronary sinus (e.g., as shown by the
arrows A in FIG. 7), and (2) its distal and proximal ends impart a
posteriorly-directed force on the walls of the coronary sinus
(e.g., as shown by the arrows P in FIG. 7). Conversely, a high
center load is imparted to the intermediate portion of elongated
body 157 (or 184) by the mitral annulus, and smaller end loads are
directed to the distal and proximal ends of elongated body 157 (or
184) by the posterior portions of the coronary sinus.
[0106] Among other things, such an effect can be created by using
an elongated body 157 (or 184) which is (1) straighter (but not
necessarily perfectly straight) than the natural curvature of the
portion of the coronary sinus adjacent to the posterior leaflet of
the mitral annulus, and (2) more rigid (but not necessarily
perfectly rigid) than the anatomical tissue which is to be
displaced by the deployed elongated body 157 (or 184).
[0107] As noted above, in order to better distribute the loads on
the proximal portions of the coronary sinus, the distal and
proximal ends of elongated body 157 (or 184) may have relatively
flexible portions 175 (FIG. 10) and/or tapers 178 (FIG. 11).
Furthermore, the flexibility of these portions can vary along their
length; thus, the elongated relatively flexible tapered portions
178 (FIG. 11) can become more flexible as they extend toward their
outer ends.
[0108] Indeed, there is nothing in the present invention which
requires that the intermediate portion of elongated body 157 (or
184) be absolutely rigid; in fact, it will function satisfactorily
so long as it is substantially resistive to the high center load
imposed by the mitral annulus. The design is further enhanced by
having the distal and proximal ends of elongated body 157 (or 184)
be somewhat less resistive to the smaller end loads directed by the
posterior walls of the coronary sinus. Thus, a satisfactory design
may be implemented with a device which has a rigidity gradient
along its length, with a highest rigidity at or near the center and
lower rigidity at or near its two ends (or, conversely, a
flexibility gradient along its length, with a lowest flexibility at
or near the center and a higher flexibility at or near its two
ends). This may be accomplished by tapering the elongated body;
and/or by varying its composition and/or material properties;
and/or by other techniques which will be apparent to a person
skilled in the art in view of the present disclosure. Or a
satisfactory design may be implemented with a device which has some
degree of flexibility along its entire length; and this flexibility
may vary with length or it may be substantially constant along the
entire length of the elongated body 157 (or 184).
[0109] Thus, as noted above, a satisfactory design may be
implemented with an elongated body 157 (or 184) which is straighter
(but not necessarily perfectly straight) than the natural curvature
of the portion of the coronary sinus adjacent to the posterior
leaflet of the mitral annulus, and (2) more rigid (but not
necessarily perfectly rigid) than the anatomical tissue which is to
be displaced by the deployed elongated body 157 (or 184).
[0110] In the system 100 described above, pushrod 109 (comprising
the straight, substantially rigid elongated body 157) is delivered
through delivery catheter 106. This construction can be
advantageous inasmuch as the pushrod 109, and particularly its
elongated body 157, can be shielded from direct contact with the
host vascular tissue as the pushrod is advanced into its working
position within the coronary sinus. As a result, the pushrod can be
moved into working position with less trauma to the host vascular
tissue.
[0111] The interior of delivery catheter 106 is typically filled
with fluid (e.g., blood) when the delivery catheter is positioned
within the vascular system of the patient. When pushrod 109 is
advanced down the interior of delivery catheter 106, this fluid is
generally forced out the distal end of the delivery catheter, with
pushrod 109 (and particularly elongated body 157) acting as
something of a piston.
[0112] Unfortunately, in some situations the distal end of delivery
catheter 106 may become partially or completely closed off. This
may occur for a variety of reasons, e.g., the distal end of the
catheter could be positioned in a narrowed-down region of the blood
vessel (FIG. 14), or the distal end of the catheter could be
orthogonally engaging the side wall of a sharply-turning blood
vessel, or the distal end of the catheter could be kinked over so
as to close off the distal end of the catheter, or another,
more-distal catheter-borne device could be blocking off the distal
end of the catheter, etc.
[0113] In these and other situations, partial or complete closure
of the distal end of the catheter can prevent fluid from escaping
from the interior of the catheter. As a result, as pushrod 109 (and
particularly elongated body 157) is advanced down the catheter, it
meets the column of fluid and, inasmuch as the fluid is
incompressible, encounters substantial resistance to advancement.
This can render the device more difficult or even impossible for
the operator to use. In addition, even where the operator can
generate sufficient force to push the fluid out the distal end of
the catheter, there is a danger that the fluid will be forced out
with such pressure that it will damage the host tissue.
[0114] In view of the foregoing, it has been discovered that it can
be advantageous to provide openings 200 (FIG. 15) in the side wall
of delivery catheter 106. The openings 200 are preferably provided
near to, but spaced from, the distal end 127 of the delivery
catheter 106, although they may also be provided substantially
anywhere along the length of the delivery catheter. The openings
200 permit fluid to escape from the interior of the delivery
catheter 106 even when the distal end 127 of the delivery catheter
is partially or completely blocked off, thus permitting easier
passage of the pushrod 109 (and particularly elongated body 157)
through a fluid filled catheter.
[0115] The aforementioned openings 200 may comprise holes 202,
longitudinally-extending slits or slots,
circumferentially-extending slits or slots 204, gills, and/or other
aperture configurations so as to form the fenestrated catheter.
[0116] Referring to FIG. 16, it will be seen that the fenestrated
catheter 106 may reside inside another catheter 173. The outer
catheter 173 is dispsed around the fenestrated catheter 106 and
spaced therefrom to define a passageway 176 between the outer wall
of the catheter 106 and the inner wall of the catheter 173. The
passageway may be annular or, if the inner catheter is not centered
in the outer catheter, may be of any configuration defined by the
two catheters, so long as the openings 200 are in communication
with the passageway. Preferably, the passageway extends to a
proximal end of the outer tube.
[0117] It should also be appreciated that the undesirable "piston
effect" described above can be ameliorated to some extent through
other constructions. For example, in system 100 shown in FIG. 3,
delivery catheter 106 may be provided with one or more
longitudinally-extending surface grooves 206 (FIGS. 17 and 18) so
as to facilitate blood flow past the perimeter of delivery catheter
106.
[0118] Similarly, in system 181, shown in FIG. 12, elongated body
184 may be provided with one or more longitudinally-extending
surface grooves 206 (FIGS. 19 and 20) so as to facilitate blood
flow past the perimeter of elongated body 184.
[0119] It is to be understood that the present invention is by no
means limited to the particular constructions herein disclosed
and/or shown in the drawings, but also comprises any modifications
or equivalents within the scope of the claims.
* * * * *